Vehicle wheel-based power generation and display systems

ABSTRACT

A power generation system is provided configured for installation within a wheel of a vehicle. The system includes a stator having a plurality of face-mounted permanent magnets; and a rotor having a plurality of windings configured to rotate, with rotation of the wheel, in proximity to the permanent magnets thereby generating a current. The stator is mounted to a brake caliper of the vehicle. Also provided is a wheel-based vehicle display system including a light emitting diode (LED) array arranged on or within a wheel of a vehicle; a power source connected thereto; and a controller connected to the LED array. The display system is configured to display at least one of: textual information, visual images or full-motion video.

RELATED APPLICATIONS

This application claims the benefit of priority under 35 U.S.C. §119(e)from U.S. Provisional Patent Application 61/852,288, entitled “VehicularInter-Wheel Electromagnetic Power Generation System”, which was filedMar. 15, 2013, the entire contents of which are incorporated herein byreference as if fully set forth.

FIELD OF THE INVENTION

The present application relates generally to vehicle wheel-based powergeneration and display systems. In particular, the present inventionrelates to an auxiliary electrical power source from an inter-wheelgenerator and the display of information, visual images and full motionvideo sequences on the rotating wheels of a vehicle.

BACKGROUND

There are various known means to generate electromagnetic power. Forexample, most generators are built with a radial flux configuration.This means that the air gap between the stator and the rotor iscylindrical. In permanent magnet generators, often the permanent magnetsrotate and are located in the interior, while the coils are stationaryand located on the exterior.

The chief advantage of this kind of generator is that because of itsubiquity, there are a large variety of off the shelf systems in manyconfigurations. However, they tend to be longer than they are wide indiameter, and most are not very efficient below 1000 RPM. This makesthem difficult to package in a wheel and use in a direct driveconfiguration at common driving speeds.

Further, there are several consumer products on the market such asflashlights that generate power via a linear motion, induced byacceleration or tilt. The wheel is constantly rotating through thegravitational field, so it is possible to use such a scheme to generateelectrical power.

However, a large sports utility vehicle (SUV) wheel at 25 mph results ina centripetal acceleration of about 10 g at 130 mm (about 5 in) from theaxis. This means that if a mass were allowed to move freely in theradial direction, the centripetal force would overwhelm the 1 Ggravitational acceleration, resulting in the mass moving to theoutermost position of the rim and staying there.

However, although the gravitational acceleration is overwhelmed by thecentripetal acceleration, there is still a 10% variation in the inertialforces on a mass at this location, which could be used to generatepower. One technique would be to attach the mass to a spring attached inthe radial direction, and use the resulting motion to drive an electricmachine. However, it would be difficult to get a very large motion,making it very difficult to harness significant electrical power thisway.

In the past two decades, reasonably priced high remanence magneticmaterials such as Neodymium-Iron-Boron (Nd—Fe—B) have become available,enabling new electric machine configurations. One of these is the axialflux permanent magnet machine, which has an air gap shaped like acircular face. These machines have seen many applications as generators,especially in small- scale wind power.

Several rear projection technologies are commercially available. Each ofthe three primary technologies—Liquid Crystal Display (LCD), DigitalLight Processing (DLP), and Liquid Crystal on Silicon (LCOS) depend on avery bright white light source and blocking spatial and color componentsof the light beam to produce an image. Even though the light source maybe very efficient, overall efficiency is reduced because light isblocked/absorbed to create the image.

A Liquid Crystal Display (LCD) creates an image by aligning liquidcrystal molecules to block or transmit light. LCD displays may be backlit-having a light source located behind the display, reflective- usingimpending light, or transflective-combining the two strategies. It isdifficult to achieve both power efficient daylight readability andnighttime readability in the same display. However, nearly all LCDs aremanufactured to have a rectangular form factor, which can be difficultto apply to a circular wheel face.

Bistable displays have pixels whose states are electrically set, butwhich maintain the set state without the application of power. Thesedisplays use little power, but cannot display video, and are not visiblewithout external lighting.

Therefore, there is a need to develop an auxiliary electrical powersource from an inter-wheel generator and a visual display ofinformation, visual images and full motion video sequences on therotating wheels of a vehicle.

SUMMARY

According to a first aspect of the invention, there is provided a powergeneration system configured for installation within a wheel of avehicle. The system includes a stator having a plurality of face-mountedpermanent magnets; and a rotor having a plurality of windings configuredto rotate, with rotation of the wheel, in proximity to the permanentmagnets thereby generating a current. The stator is mounted to a brakecaliper of the vehicle.

According to another aspect, there is provided a wheel-based vehicledisplay system including a light emitting diode (LED) array arranged onor within a wheel of a vehicle; a power source connected thereto; and acontroller connected to the LED array. The display system is configuredto display at least one of: textual information, visual images orfull-motion video.

According to a yet further aspect, there is provided a power generationsystem configured for installation within a wheel of a vehicle, thesystem including a stator, mounted to a brake caliper of the vehicle,the stator having a plurality of face-mounted permanent magnets; and arotor having a plurality of windings configured to rotate, with rotationof the wheel, in proximity to the permanent magnets thereby generating acurrent, which is connected to a wheel-based vehicle display system,which includes a light emitting diode (LED) array arranged on or withinthe vehicle wheel; and a controller connected to the LED array, thedisplay system is configured to display at least one of: textualinformation, visual images or full-motion video.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description of the preferred embodiment of thepresent invention will be better understood when read in conjunctionwith the appended drawings. For the purpose of illustrating theinvention, there are shown in the drawings embodiments, which arepresently preferred. It is understood, however, that the invention isnot limited to the precise arrangements and instrumentalities shown. Inthe drawings:

FIGS. 1A and 1B depict a wheel-based display system in accordance withthe present invention in use on a vehicle;

FIG. 2 depicts a first embodiment of the wheel-based display system inaccordance with the present invention;

FIG. 3 is a schematic depiction of an electromagnetic power generationsystem in accordance with the present invention;

FIG. 4 is a second embodiment of the wheel-based display system inaccordance with the present invention; and

FIG. 5 is an exploded view of the electromagnetic power generationsystem in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Introduction to theEmbodiments

Certain terminology is used in the following description for convenienceonly and is not limiting. The words “right,” “left,” “top,” and “bottom”designate directions in the drawings to which reference is made. Thewords “a” and “one,” as used in the claims and in the correspondingportions of the specification, are defined as including one or more ofthe referenced item unless specifically stated otherwise. Thisterminology includes the words above specifically mentioned, derivativesthereof, and words of similar import. The phrase at least one followedby a list of two or more items, such as “A, B, or C,” means anyindividual one of A, B or C as well as any combination thereof.

The power generation system as shown and described herein provides asafe and sustainable means of generating, storing and dispensingelectric power entirely independently of the primary vehicular battery.This independent and sustainable power source can then be used foradditional electrical applications while the vehicle is in motionwithout draining the vehicle's battery. Such uses have potentiallyendless applications, and include but are not limited to: a vehicularwheel based communications, rotational and non-rotational billboardimage display, broadcast video display system, silent video alarm andautomotive security system, vehicular wheel broadcasting, entertainment,and inter-vehicle communications network.

A force based power generation design can be contemplated. Approximatelyone quarter of the vehicle weight is supported by each wheel. In thecase of a large sports utility vehicle (SUV) (e.g. GMC Yukon®, CadillacEscalade®) with a curb weight of over 5,367 lbs, that means that anaverage of 1,342 lbs is on each wheel. This force is applied from thehub of the wheel through its structure and the tire to the ground.

As an example, the wheel rotates 8.72 times per second at 25 mph on anEscalade, meaning that 11.47 Joules must be generated in each flip toproduce 100 W. This means that a 1342 lb (5879N) load would have to belifted 1.92 mm/rotation. Some materials, such as piezo ceramics andelectroactive polymers, are effective for small displacement, high forcepower generation. However, this deflection would probably require a verytall and expensive piezo stack.

Tire deflection is also contemplated as a power generation design, wherethe outer wall of the tire moves several mm with each rotation. Itshould be possible to harness this motion to generate power. This couldbe accomplished electromechanically by placing some mechanism in thepressurized chamber. Another method would be to create a series ofsealed pressure chambers inside the tire, and allow air to flow betweenthem using some kind of turbine.

Thermal power generation is also considered since both the tire and thebrakes generate a fair amount of heat that is dissipated into theenvironment. Because of this, there is a temperature differential, whichmay be harnessed to generate electricity. One means of doing this is touse a thermoelectric material to generate power directly. Another meansis to employ a heat engine to create mechanical power that may drive anelectrical machine.

The power generation system generates electricity for storage and useduring and as a result of the rotation of the vehicles wheels when thevehicle is in motion during the normal driving and vehicular use.

The power generation system can be custom built into a range of sets ofwheels designed for use on most foreign and domestic four wheel and twowheel vehicles regardless of lug nut configuration including but notlimited to cars, sport utility vehicles, trucks, buses and motorcycles.

Additional mass was a consideration, since adding too much mass to thewheel will interfere with the proper functioning of the suspension.Essentially, a large mass, because of its inertia, can overwhelm thesuspension springs and cause the tires to no longer reliably contact theroad over height variations such as potholes. Describing how much massis too much is dependent on the individual vehicle suspension andrequires in depth analysis. As an example, a benchmark was selectedbased on reports of a Chevrolet S-10® pickup with in-wheel electricmotors as part of a hybrid electric retrofit. This installation wasreported to add 33 lbs to each wheel, and was possible withmodifications to the suspension system. Since it is undesirable torequire suspension modifications as part of the LED Wheels installation,it is desirable to keep the net increase to the unsprung mass less than33 lbs.

By providing a sustainable power source and a method of generating,storing and dispensing electric power entirely independently of thevehicular battery, the power generation system provides the vehicleowner with a means of installing and operating a variety of electricaldevices, including but not limited to: a set of wheel basedcommunications and broadcast video display systems with minimalalterations to the vehicle greatly reducing the manpower and expensesentailed in installing and operating a set of wheels containing thewheel based communications and broadcast video display system.

The wheel-based communications and broadcast video display systemrequires power connected to a display, which will be mounted on a movingwheel on a passenger car or other moving vehicle.

Light Emitting Diodes (LEDs) are semiconductor light sources thatusually produce a single color of light. Composite LED components areavailable combining a red, green, and blue LED that together can producean arbitrary color. An adequate number of LED's put together can producean image. Relative to other means of display, LED's have relatively goodluminous efficacy, in the range of 4-10 lm/W for practical colordisplays.

Specifically, RGB LEDs are advantageous because of their powerefficiency, robustness, and flexibility to create difference geometries.Unlike technologies such as LCD, LEDs are typically purchased asindividual components, each consisting of one pixel. This results in afair amount of manufacturing overhead to build an array, but also meansthat there is more freedom to make the form factor and control match theapplication. A fair example of an RGB LED is the Seoul SemiconductorUBMGSRT8213, available in a 2.6 mm×3.2 mm package.

DETAILED DESCRIPTION

In FIG. 1A, a vehicle 100 with the wheel-based communications andbroadcast video display system installed is shown in an alarm orsecurity mode. The front and rear wheel displays 102, 104 displaywarning indicia, which deter a would-be perpetrator 106. In this case,the image “911” is displayed thereby indicating an emergency situationin which assistance is required.

FIG. 1B depicts a vehicle with the wheel-based communications andbroadcast video display system installed, which is shown in a billboardmode. The front and rear wheel displays 102, 104 display, in this case,promotional material/information. It should be noted that the displaycan be daylight or nighttime readable, provides a quality image, and canoperate continuously under normal vehicular driving, stationary andparked conditions.

Daylight readability greatly increases the amount of time during whichthe wheels can be delivering content. For the outdoor signage industry,a brightness of at least 5000 Nits (cd/m2) is recommended. Given a90-degree viewing angle, this yields 9200 lm/m2. For a 16″ display, thismeans about 1200 lm. 5000 Nits is a figure for signs to be visible frombillboard distances; given that wheels will primarily be observed atcloser range, a smaller figure will likely suffice.

As shown in the embodiment of FIG. 2, the wheel 200 includes a pluralityof spokes 204, which emanate radially from a central portion of thewheel 200. Interposed between the spokes 204 are slots or vents 212,which permit the dissipation of heat therethrough. The brakes generate agreat deal of heat, and a generator and display can generate asignificant amount of additional heat. The vents 212 therefore providefor adequate cooling, primarily through airflow, so that no componentexceeds its design temperature.

In the embodiment of FIG. 2, LEDs 202 are arranged on the wheel alongthe spokes from a central portion of the wheel 200 to create an array.To facilitate fabrication and control, a series of identical spokes 204radiate from the center of the wheel. Each spoke comprises a PrintedCircuit Board (PCB) with its own microcontroller. By making many ofthese identical boards for each wheel, good economies of scale mayquickly be obtained.

Since, when the vehicle 100 is in motion, the display 102, 104 spinswith the wheel 200, the design is greatly simplified. Spinning thedisplay 102, 104 also allows for a better picture quality with fewerLEDs 202 thanks to a Persistence of Vision (POV) effect. In order tocontrol such a spinning display, it is necessary to determine theprecise angular orientation of the wheel at all times. Fortunately, thepower generation system described below results in a regular periodicelectrical waveform. With a single precise Hall effect sensor/magnetpair to define a home position, this periodic signal provides preciseangular orientation.

The LED arrangement in FIG. 2 is represented by 40 spokes 204 havingapproximately 32 LEDs 202 each. The spokes 204 are shown as having widerspacing between LEDs near the center so that the pixel density isrelatively consistent. While the wheel 200 is moving, the image qualitywill increase as the POV effect allows the interpolation of the spacesbetween the spokes 204. At maximum brightness, these LEDs consumeapproximately 190 mW each, yielding a luminous efficacy of 6.8 lm/W.

The resolution of the static image could be increased by adding morespokes of less than the full radial length near the rim. This would fillin the largest spaces between pixels.

In the embodiment shown in FIG. 4, the wheel 200′ has an array 214 ofLEDs, which are arranged on an outward facing portion 230 of the wheel200′. In this embodiment, the wheel 200′ does not include 40 radiallyextending spokes as in FIG. 2, rather only 5 spokes 204′, which connectthe outward facing portion 230 of the wheel 200′ including the LED array214 to the outer circumference of the rim 228.

As in the embodiment shown in FIG. 2, the wheel 200′ of FIG. 4 likewiseincludes slots or vents 212 to dissipate heat generated by motion andbraking of the wheel.

It is noted that in order to provide adequate luminous intensity at thewheel 200, 200′, it is possible to create a backlit display 102, 104using LCD or other technology in which the light source is located onthe non-rotating part of the vehicle 100 and the display it illuminatesis located on the rotating portion.

Turning now to FIGS. 3 and 5, a wheel-based power generation system isshown. An axial flux permanent magnet generator is used to takeadvantage of the geometry of the wheel and the low rotational speed. Inorder to keep the generator mechanically simple, a single rotor 224,226, single stator 218, 222 design is provided. The stator includesface-mounted permanent magnets 222 mounted to a magnet-mounting disc218, and the rotor includes sunflower configured copper windings 226mounted to a windings mounting disc 224.

FIG. 3 shows an interior view of wheel 200, 200′ where a magnet mountingdisc 218 is secured to a brake caliper 208 of the vehicle via a mountingbracket 210. The magnet-mounting disc 218 carries permanent magnets 222and surrounds brake disc 206.

Wedge shaped magnets 222 can be used in order to maximize usage of thestator face. Twenty-four (24) of these magnets form a 12-inch diameterdisc shape with an 8-inch diameter hole. The magnets 222 are much moreeffective with a steel core 218 backing them to form a complete magneticcircuit. Because this core moves with the magnets, the magnetic fieldwill not vary greatly inside it and there is little propensity forparasitic losses. Therefore, a piece of ordinary plate steel, e.g. cutwith a water jet, is an effective solution.

In order to provide 300 Watts of mechanical power at 262 RPM, 11 N-m oftorque must be applied. In order to provide torque to the wheel-basedpower generation system, the mounting bracket 210 is connected to thebolts that secure the brake caliper 208. These bolts vary somewhat insize and position, however, since the forces on the mounting bracket 210will not be too great, a simple stamped sheet metal part may be used totransmit the forces. Most brake calipers 208 are attached via two boltsapplied from the direction facing the center of the vehicle 100.Although the bolt pattern for the brake calipers vary somewhat, it couldbe fairly economical to produce and stock a variety of the brackets 210for different vehicles and the final installer may modify the part oreasily fabricate an original one for unusual applications.

FIG. 5 is an exploded view of the wheel-based power generation system. Amounting bracket 210 attached to a brake caliper 208 of the vehicle 100,within which brake disc 206 rotates. A plurality of permanent magnets222 are mounted to a magnet mounting disc 218 or steel core, defining astator, which is mounted on the mounting bracket 210, thereby preventingthe magnets from rotating. In order to use a simple lightweight bracket210 to carry the generator torque, it is necessary to constrain thestator against the wheel 200, 200′ so that it is constrained in otherdirections. The stator is constrained by a bearing 216 having at least a7-inch inner diameter to fit outside a lug circle of the vehicle's wheelhub.

In order to simplify the construction of an initial prototype, asingle-phase rotor 224, 226 was designed. With one coil per pole wiredin series, and 24 windings per coil, this armature should provide about40 Volts even at speeds as low as 25 mph.

As with the magnets 222, the generator performance will be greatlyenhanced with a steel backing for the windings 226. However, because themagnetic field is time varying for this component, parasitic losses areof significant concern. Therefore, a solution is to use a wound ribbonof high silicon magnet steel to create a laminated core. Alternatively,sintered magnet steel may be an appropriate material for a mass producedrotor core.

The rotor 224, 226 is mounted in the wheel 20, 200′ and rotates with thewheel 200, 200′ in proximity to the permanent magnet stator 218, 222thereby generating a current. The current generated can be stored in abattery 220 or can be directed to power the above described wheel-basedcommunications and broadcast video display system or other device of thevehicle.

In order to switch the LEDs of the wheel-based communications andbroadcast video display system, a reliable high current rail at 5-10 VDCis necessary. The wheel-based power generation system will typicallyproduce power at 40-100 VDC rectified. Therefore, some power controlelectronics are necessary. DC-DC conversion circuitry has made greatadvances in the last several years, so it is likely that some kind of“buck” conversion circuit can be coupled with an intelligent model ofgenerator performance to balance power between the display 102, 104 andbattery 220.

Electronics are necessary on the wheel 200, 200′ for power control,communications, and driving the display 102, 104. Since none of thesesystems need be especially bulky, there are two main volumes availablefor this purpose. The first being the space in front of the lugs, whichmount the wheel 200, 200′ to the hub of the vehicle 100. The secondbeing the annulus between the generator and the rim 228. It may also beappropriate to locate communications and display drivers in the lugspace, and power control along with the battery 220 in the annulus.

Alternatively/additionally, electrical power may also be transmittedfrom the vehicle electrical system to the wheel via a coupling. Thiscoupling may take the form of copper moving against carbon brushes, orcopper slip rings. Several geometric configurations are possible.

Alternatively/additionally, electrical power may also be transmittedfrom the vehicle electrical system to the wheel via an electricaltransformer in which the primary coil is located on the non-rotatingpart of the chassis and the secondary is located on the wheel. Such anelectrical device may be configured to perform independent of therotation, or it may be possible to harness a small amount of power fromthe rotation.

It is understood, therefore, that this invention is not limited to theparticular embodiments disclosed, but is intended to cover allmodifications which are within the spirit and scope of the invention asdefined by the appended claims; the above description; and/or shown inthe attached drawings.

What is claimed is:
 1. A power generation system configured forinstallation within a wheel of a vehicle, the system comprising a statorcomprising a plurality of face-mounted permanent magnets; and a rotorhaving a plurality of windings configured to rotate, with rotation ofthe wheel, in proximity to the permanent magnets thereby generating acurrent, wherein the stator is mounted to a brake caliper of thevehicle.
 2. The power generation system of claim 1, further comprising abattery, wherein the current generated is stored in the battery.
 3. Thepower generation system of claim 1, wherein the stator is mounted to abracket, which is mounted to the brake caliper of the vehicle.
 4. Thepower generation system of claim 3, wherein the magnets of the statorare mounted to a disc, which is mounted to the bracket.
 5. The powergeneration system of claim 4, wherein the mounting disc is made ofsteel.
 6. The power generation system of claim 4, wherein the magnetsare wedge-shaped.
 7. The power generation system of claim 1, wherein therotor is comprised of copper windings in a sunflower configuration. 8.The power generation system of claim 1, wherein the rotor is asingle-phase rotor and comprises a steel backing for the coils.
 9. Thepower generation system of claim 8, wherein the backing is mounted tothe vehicle wheel.
 10. A wheel-based automobile display systemcomprising a light emitting diode (LED) array arranged on or within awheel of a vehicle; a power source connected thereto; and a controllerconnected to the LED array, wherein the display system is configured todisplay at least one of: textual information, visual images orfull-motion video.
 11. The display system of claim 10, wherein the wheelcomprises a plurality of spokes, which radiate from a center portion ofthe wheel and wherein the LEDs are arranged on the spokes.
 12. Thedisplay system of claim 10, wherein the vehicle wheel comprises aplurality of center radiating spokes, each spoke comprising a printedcircuit board having a microcontroller.
 13. The display system of claim10, further comprising a power controller; a communications interfaceand a display driver located within an annulus of the rim of the vehiclewheel.
 14. The display system of claim 10, wherein the textualinformation, visual images or full-motion video are displayed with aPersistence of Vision (POV) effect while the vehicle wheel is rotating.15. The display system of claim 10, wherein the display system isconfigured as a security system, which displays alerts if the vehicle isstolen or if assistance is needed.
 16. The display system of claim 10,wherein the system displays promotional information.
 17. A powergeneration system configured for installation within a wheel of avehicle, the system comprising a stator, mounted to a brake caliper ofthe vehicle, the stator comprising a plurality of face-mounted permanentmagnets; and a rotor having a plurality of windings configured torotate, with rotation of the wheel, in proximity to the permanentmagnets thereby generating a current, which is connected to awheel-based automobile display system, which comprises a light emittingdiode (LED) array arranged on or within the vehicle wheel; and acontroller connected to the LED array, the display system is configuredto display at least one of: textual information, visual images orfull-motion video.
 18. The power generation system of claim 17, whereinthe stator is mounted to a bracket, which is mounted to the brakecaliper of the vehicle.
 19. The power generation system of claim 17,wherein the wheel comprises a plurality of spokes, which radiate from acenter portion of the wheel and wherein the LEDs are arranged on thespokes.
 20. The power generation system of claim 17, wherein the displaysystem is configured as a security system, displaying alerts if thevehicle is stolen or if assistance is needed.